Automated telephone answering systems are known. These systems are capable of delivering prerecorded messages and of receiving inputs from the caller either in the form of signals from the telephone, such as the Touch Tone or rotary dial signals, or voice messages from the caller. These systems communicate with humans either directly by producing the sounds of human speech or indirectly through signals which are interpreted by an electrical or electromechanical device.
An automated telephone system generally consists of an input module, a control module, and an output module, even though the line of distinction is sometimes not clear. The control module may be the CPU of a computer while the input and output modules are combined in a single input-output processor (IOP) which may also be located in the computer.
An input is most often the Dual Tone Multi Frequency (DTMF) known commonly by the trademark Touch Tone. Normal speech is used as an input to those systems which incorporate either speech recognition or the assistance of human operators. A simple form of speech recognition, frequently used, provides a binary signal to indicate the presence or absence of normal speech. Another input signal is the teletype, which generally includes the use of a MODEM.
The most common output is speech, but teletype with the use of a MODEM is also common.
The control module determines which event to initiate upon completion of a previous event. An "event" consists of an action initiated by the automated telephone system and a response. For the purposes of the instant invention, the action of interest is the communication of speech and teletype. The response generally comes from the caller, but need not, and some actions do not require a response.
For example, the action may be a message asking the caller to press one of several telephone buttons to obtain selected information. ("Press 1 for information about patents.") The response consists of signals representing the button pushed. In a complicated system, the action of the subsequent event is a function of the response to the first action.
There are several ways to store the instructions for the control unit. A preferred system, for example, stores the instructions in an M.times.N "instruction" or "message" matrix. Each row of the matrix, 1 through M, corresponds to an event, while the columns, 1 through N, correspond to a response to the event such as a Touch Tone entry or to no entry at all. One exemplary matrix has over one thousand rows and 11 columns.
The input/output hardware typically consists of a telephone line interface, a microprocessor, a DTMF detector, digital-to-analog and analog-to-digital converters, and associated electronics. Often, the electronics include data compression chips to reduce the amount of memory required by digitized messages.
An important device used with these telephone systems is the Telecommunications Device for the Deaf, or "TDD", which is used by those with a hearing impairment. These are special teletype terminals which provide a cradle to receive a regular telephone handset. The terminal is equipped with a keyboard and a display screen. These systems are limited to communication with other TDD systems, a TDD caller being unable with present equipment to call a private business exchange (PBX) switchboard.